AU715819B2 - Cleaning systems - Google Patents

Description

WO 97/13591 PCT/GB96/02460 CLEANING SYSTEMS The present invention relates to cleaning systems and more particularly to a cleaning system for discharging a cleaning solution under pressure.

The present invention seeks to provide a cleaning system for discharging a detergent solution or other cleaning solution for heavy duty usage as may be required for example in the mining, construction, and transport industries for cleaning or degreasing vehicles and equipment.

Certain currently available cleaning systems for heavy duty usages such as those specified above are unable easily to provide a sufficiently high concentration of detergent or other cleaner within the solution with the result that for some applications where the vehicles or equipment to be cleaned are especially dirty or greasy the cleaning action is of reduced efficacy and increased time and increased quantities of water may be required to achieve effective cleansing.

According to the present invention, there is provided a cleaning system comprising mixing means for connection to a source of water under pressure and to a source of cleaning liquid for mixing with the water, said mixing means comprising a venturi through which the incoming water passes, said system further comprising pump means for feeding the cleaning liquid under pressure into the throat of the venturi for mixing with the incoming water in proportions dependent on the characteristics of the venturi.

In a preferred embodiment of the invention, the mixing means comprises a chamber into which the venturi discharges, said chamber being arranged for connection to a source of pressurised air whereby the resulting mixture is discharged as a foam.

Advantageously, the pump means may be an air-actuated pump also connected to the source of pressurised air.

WO 97/13591 PCT/GB96/02460 -2- Preferably, the cleaning liquid is pumped into the venturi throat via a metering orifice which can be adjusted in order to vary the proportions of the mixture.

The cleaning liquid may comprise a detergent, a solvent, a degreaser or any other cleaner capable of removing dirt or grease.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is a schematic circuit diagram of a cleaning system in accordance with the preferred embodiment of the invention; and Figure 2 shows, schematically, a mixing and proportioning unit incorporated within the system.

In accordance with the preferred embodiment of the invention, a cleaning system for heavy duty usages such as those previously discussed comprises a mixing and proportioning unit 2 in which detergent or other cleaning liquid or solvent (hereinafter referred to, simply, as "detergent") is mixed with water in the required concentration to form a solution which is mixed with air under pressure to be discharged as a foam from a nozzle 4. The mixing and proportioning unit 2 comprises a venturi 6 (see Figure 2) having an inlet 8 connected either to a mains water source or other source of pressurised water via a pipe 10. Liquid detergent is fed into the venturi 6 through an inlet 12 in the zone of the throat of the venturi 6. The water and liquid detergent are discharged from the venturi 6 into a mixing chamber 14 which also has an inlet 16 for pressurised air. The liquid detergent and water are thoroughly mixed during passage through the mixing chamber 14 and the injection of pressurised air into the chamber 14 causes the resulting solution to be discharged as a foam.

In previously proposed cleaning systems, the detergent liquid is drawn into a proportioning venturi by a suction effect created by the reduced pressure which exists within the throat of the venturi. In the system of the present invention, the liquid detergent is pumped under pressure into the venturi. For this purpose the system incorporates a pump 18, WO 97/13591 PCT/GB96/02460 -3the pump 18 preferably being an air-actuated pump which is connected to an air inlet line which also supplies the compressed air to the mixing chamber 14. Any suitable air actuated pump may be used for this purpose; by way of example a suitable pump is a diaphragm pump as manufactured by Grayco Inc. of Minneappolis, U.S.A. A pressure regulator 22 is used to adjust the air pressure supplied to the pump 18. The inlet 24 of the pump 18 is connected to a source of liquid detergent and the outlet of the pump 18 is connected to the throat of the venturi 6 via a supply line 26. The relative proportions of the water and liquid detergent in the solution formed within the mixing chamber 14 will depend on the ratio of the inlet and throat diameters of the venturi 6 and also on the relative inlet pressures of the incoming water and liquid detergent and these relative inlet pressures can be adjusted by means of a water pressure regulator 30 upstream of the venturi 6 and also by means of the pressure regulator 22 which controls the supply of air to the pump 18. Further control of the proportions is provided by an orifice plate 32 (see Figure 2) incorporated in the supply line 26 immediately upstream of the venturi throat. The orifice plate 32 is removable so as to be replaceable by alternative orifice plates with different sizes of orifice therein. The pressure of the air fed into the chamber inlet 16 can be controlled by a pressure regulator 34.

By feeding the liquid detergent under pressure into the proportioning venturi 6 a cleaning solution having a high concentration of liquid detergent can be obtained. By way of example, with a system such as this we are able to obtain a concentration of liquid detergent in a ratio as high as 3:2 to 2:3 (liquid detergent to water) whereas in prior systems it was difficult to achieve a ratio significantly better than 1:7 (liquid detergent to water).

However, by appropriate selection of the size of the orifice plate 32 a lower ratio of down to about 1:4 can be obtained for applications where the higher concentrations are not needed.

The entire system including mixing and proportioning unit 2 and pump 18 can be selfcontained and portable, with inlets for connection to a mains or other pressurised water supply, a compressed air supply, and a source of liquid detergent.

Although the system described incorporates an air-actuated pump which is advantageous because the system uses compressed air in order to generate foam, nevertheless this is not essential and other suitable forms of pump could alternatively be used.

The embodiment has been described by way of example only and modifications are possible within the scope of the invention.

Throughout this specification and claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers or steps but not the exclusion of any other integer or group of integers.

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Claims (11)

1. A cleaning system comprising mixing means for connection to a source of water under pressure and to a source of cleaning liquid for mixing with the water, said mixing means comprising a venturi through which the incoming water passes, said system further comprising pump means for feeding the cleaning liquid under pressure into the throat of the venturi for mixing with the incoming water in proportions dependent on the characteristics of the venturi. 10

2. A cleaning system according to claim 1, wherein the mixing means further comprises o* a chamber into which the venturi discharges, said chamber having an inlet arranged for connection to a source of pressurised air whereby the resulting mixture is discharged as a foam. *o* 15

3. A cleaning system according to claim 2, wherein the pump means is an air-actuated pump also connected to the source of pressurised air. *o °h

4. A cleaning system according to any one of claims 1 to 3, wherein the pump means is operative to pump the cleaning liquid into the throat of the venturi via a metering orifice.

A cleaning system according to claim 4, wherein said metering orifice comprises a replaceable orifice plate.

6. A cleaning system according to any one of claims 1 to 5, further comprising means for controlling the pressure of the cleaning liquid.

7. A cleaning system according to any one of claims 1 to 6, further comprising means for controlling the pressure of the incoming water. r 7 0

8. A cleaning system according to claim 2 or any claim dependent on claim 2, further comprising means for controlling the pressure of the air feed into the inlet of the chamber. P:\OPER\PSH\72220-96.SPE 30/11/99 -6-

9. A method of generating a cleaning solution under pressure, comprising feeding water and cleaning liquid into a system according to any one of the preceding claims and discharging the mixture under pressure.

10. A method according to claim 9, wherein the water and cleaning liquid are mixed in a ratio within the range of 3:2 to 2:3.

11. A cleaning system substantially as hereinbefore described with reference to the accompanying drawings. DATED this 30th day of November, 1999. CASTROL LIMITED 9oe By its Patent Attorneys: 15 DAVIES COLLISON CAVE 9b